FIG. 6 and FIG. 7 are plan views showing the construction of a conventional paper folding fan.
As shown in FIG. 6 and FIG. 7, a plural number of fan-shaped paper pieces 21, in which one side of the paper piece 20 is folded in the shape of a valley at a bend line 22 and the other side of the paper piece 20 is folded in a conical shape at a bend line 23, are placed one upon another, and are connected to one another by a grommet at one end in a mutually movable way. Here, the respective fan-shaped paper pieces 21 are placed one upon another in such a way that the part folded in the shape of a valley 24 of the fan-shaped paper piece on the under side bites with the part folded in a conical shape 25 of the fan-shaped paper piece on the upper side.
If you open this paper folding fan to the left and right by holding it at the fan-shaped paper piece 21 at the top and bottom ends of the fan, the part folded in the shape of a valley 24 of the fan-shaped paper piece on the under side and the part folded in a conical shape 25 of the fan-shaped paper piece on the upper side bite with each other, and the top of the fan-shaped paper pieces 21 are displaced sideward one after another to open the paper folding fan. If the folding fan is designed in a way to show an advertisement of some specific enterprise in such an open state, and used by spectators at a sports stadium, etc., it serves as an advertisement medium. Moreover, even in the case without printing of an advertisement, the folding fan has the function of an ordinary folding fan.
The bend line of the fan-shaped paper pieces of the conventional paper folding fan of this type was not determined by any specific rule but was decided arbitrarily by the manufacturing worker. For that reason, it was often the case that, when the paper fan is opened, a deviation of biting is produced at the intermediate part as shown in FIG. 9 if the tip of the fan-shaped paper pieces is made to bite accurately as shown in FIG. 8. Moreover, depending on the position of the bend line, a deviation of biting *produced at the tip of the paper pieces are made to bite accurately at the intermediate part conversely. On the other hand, if you try to fit the biting of the folded parts accurately, it produces a deviation of the center position, thus causing a loss of function of the folding fan. The conventional type of folding fan did not sufficiently discharge the function of a folding fan of a single-sheet shape because of poor fitting at the folded part as described above, making the fan-shaped paper float up when the paper folding fan is opened, and also because of poor strength due to insufficient biting.
Although it is possible to form fan-shaped paper pieces capable of compensating for said defects comparatively easily if the paper piece 20 before folding is formed in a fan shape, an extra work of cutting the material paper into a fan shape is required in this case, thus producing a defect of increasing the working processes. On the other hand, if you use fan-shaped paper pieces made from paper pieces of a rectangular shape 20, it makes said defect appear conspicuously although the number of processes decreases.
The object of the present invention, proposed in view of said circumstance, is to provide a folding fan capable of ensuring an accurate fitting of the folded parts and having a sufficient strength as a folding fan of a single-sheet shape.